Apparatus for explosive charge drilling



P 27, 1966 L. H. ROBINSON, JR., ETAL 3,274,933

APPARATUS FOR EXPLOSIVE CHARGE DRILLING Filed May 24, 1963 2 Sheets-Sheet 1 .H s 1 \p: l6- l9 DELAY SAND con.

/BAT;7ERY 53- 53 53 47- BLASTING 47 I CAPS 56 I 6 56 h 55 2 54 I 2 r FIG. IA. EXPLOSIVE/ 65 1- BLASTING CAP -EXPLOSIVE Fl INVENTORJ.

LEON H. ROBINSON,JR.,

BY ROBERT H. FFHEDMAN.

ATTORNEY.

p 1966 L. H. ROBINSON, JR., ETAL 3,

APPARATUS FOR EXPLOSIVE CHARGE DRILLING 2 Sheets-Sheet z Filed May 24, 1963 E P P L L 5 R D G N S U o H E L U s P A c DRILLING H 0/? IN 5:5:EEHJE HH FORMATION DETRITUS FIG. 4.

FIG. 3.

INVENTORJ. LEON H. ROBINSON JR.- ROBERT H- FRIEDMAN 9 BY A TTOR NEY.

United States Patent 3,274,933 APPARATUS FOR EXPLOSIVE CHARGE DRILLING Leon H. Robinson, Jr., and Robert H. Friedman, Houston,

Tex., assignors, by mesne assignments, to Esso Production Research Company, Houston, Tex., a corporation of Delaware Filed May 24, 1963, Ser. No. 284,775 4 Claims. (Cl. 10221.6)

This invention relates generally to drilling boreholes with explosive charges, and more particularly to drilling boreholes with a combination of shaped charges and nondirectional gauging charges.

The technique of drilling boreholes with a predetermined sequence of shaped charges and gauging charges is described in U.S. Patent No. 3,070,010, Robinson. In this technique the jet charges and gauging charges are injected into a stream of drilling fluid going down a well pipe. Each shaped charge pumped down the pipe is followed by one or more gauging charges. After the shaped charge is seated at the bottom of the well pipe, the explosive portion of the charge is spaced from the bottom of the borehole, and the explosive charge is detonated. A gauging charge is thereupon injected into the hole left by the preceding shaped charge so as to extend as far as possible thereinto. Preferably, the gauging charge is long enough to extend substantially the entire length of the hole blasted by the shaped charge. The gauging charge is detonated and blasts a hole of substantially uniform diameter. Drilling fluid is circulated after each detonation of each shaped and gauging charge so as to remove earth fragments and fragments of the explosive charge housings.

While the drilling technique described above in general terms has been found to be quite satisfactory, certain problems have arisen in practice. For example, a substantial portion of the energy produced by the nondirectional explosive charge is directed upwardly and serves only to blow drilling fluid up the borehole. Manifestly, it Would be desirable for as much as possible of this energy to be directed laterally of the borehole in order to most economically and effectively use the explosive material available in the explosive charge.

In accordance with one aspect of this invention, there is provided an elongated housing having a first nondirectional explosive charge at one end thereof. Positioned in the housing directly above the nondirectional explosive charge is a second nondirectional explosive charge formed generally like a cup and extending upwardly and away from the longitudinal axis of the elongated housing. Within the second charge is means for reflecting outwardly the energy produced upon detonation of the second charge. Connected to the first and second charges is means for detonating the second charge a predetermined interval after the first charge is detonated such that the upwardly-going energy produced by the first charge is deflected outwardly into the surrounding earth formation by the energy proudced by the second charge.

The invention will be further described with reference to the drawings, wherein:

FIGS. 1A and 1B are sectional views illustrating a preferred embodiment of the invention;

FIG. 2 is a cross-sectional view taken along section 2-2 of FIG. 1B; and

FIGS. 3 and 4 are a simplified cross-sectional view of 3,274,933- Patented Sept. 27, 1966 a portion of a well installation illustrating the utility of the present invention.

With reference now to the embodiment of the invention illustrated in FIGS. 1A and 1B, there is shown an elongated housing 11, which preferably is formed from an electrically conductive material such as aluminum for reasons that will become apparent below. Disposed in the lower end of the housing 11 is a nondirectional explosive charge 13 which may be of an explosive material such as RDX, TNT, PETN, ammonium nitrate, or combinations of any two or three of these. In the upper end of the mass of explosive material 13 is an electrically activated blasting cap 63 for detonating the explosive material 13.

Positioned immediately above the explosive material 13 and spaced therefrom by a distance of from 1 to 12 inches is a generally cup-shaped mass of exploive material 12 which may be the same type as explosive mass 13. The cup-shaped explosive material 12 is held within a housing therefor comprising a lower liner 61 and an upper liner 59 having an annular flange 55 connected to the upper end thereof. Both liners may be of a frangible plastic or of a light metal such as aluminum which may be easily circulated out of the borehole when shattered by the explosion of explosive mass 12. A number of holes 54 are drilled in the flange 55, and blasting caps 56 extend .therethrough for detonating the cup-shaped explosive charge 12. Held within a liner 52 and filling the cup volume within liner 59 is a quantity of a material such as sand to act as a backup for liner 59 so that most of the energy produced upon detonation of explosive charge 12 will be reflected outwardly.

Disposed in the upper end of housing 11 is apparatus for detonating blasting caps 63, and for detonating the blasting caps 56 a predetermined time interval after de tonation of blasting caps 63. This apparatus is res-ponsive to a predetermined differential pressure between the inside and outside of housing 11. As illustrated, the apparatus comprises a rod 27 held in place by a shear pin 31, and terminating at its lower end in a spring biased over-travel plunger 29. Supported on laterally extending wall 38 are a pair of electrical contacts 41 and 43 which are positioned immediately below over-travel plunger 29. An electrically conductive bridging member 45 at the lower. end of over-travel plunger 29 is adapted to engage contacts 41 and 43 so as to complete an electrical circuit between the contacts. Contact 41 is connected to a battery 37; the other terminal of the battery 37 is connected to the electrically conductive housing 11. The other contact 43 is connected directly to the blasting cap 63 by means of electrical lead 47. Contact 43 also is connected to each of blasting caps 56 through electrical lead 49, delay coil 51, and a plurality of branching electrical leads 53. The function of the delay coil is to delay the rise in electrical current produced when conductive bridging member 45 bridges the gap between contacts 41 and 43 so that blasting caps 56 will be activated a predetermined interval of time after activation of blasting cap 63.

Electrical lead 47 extends through the explosive mass 12 and is insulated therefrom by an electrically insulating sleeve 65.

Rod 27 is disposed in a chamber 20 formed by a generally cylindrical inner housing member 16. The chamher 20 is of greater diameter at the lower end thereof than at the upper end thereof to form a shoulder 22. The rod 27 has a cross head or plate 25 connected to the upper end thereof. A plunger comprising piston 17, cross head or plate 21, and connecting rod 18, is disposed in the upper end of chamber 20. The piston 17 is provided with a piston ring 19 adapted to provide a sliding seal with the walls of the cylinder. The cross head 21 engages shoulder 22 so that the plunger is held within the chamber 20. A compression spring 23 is disposed between cnoss heads 21 and 25. Port 33 provides fluid communication between the lower end of chamber 20 and the annular chamber between housing member 11 and inner housing member 16. When a predetermined differential pressure exists between the inside and outside of the housing 11, the plunger will be forced downwardly until shear pin 31 is sheared, thereby forcing rod 27 downwardly until bridging member 45 bridges the gap between contacts 41 and 43.

The operation of the apparatus described above will be best understood by referring to FIGS. 3 and 4. In the figures there is shown a borehole 2 having disposed therein a drill pipe which may terminate in a drilling head 7 having a drill bit, which may be a diamond drill bit, at the lower end thereof. The drilling head 7 is provided with an annular bore which preferably is only slightly larger than the maximum outside diameter of the housing 11.

As described generally above, a shaped charge capsule is initially pumped down the drill pipe 5 in the drilling fluid 3 until it is landed at the bottom of the well bore. When it is detonated, as by increasing the pressure of the drilling fluid to actuate a differential pressure responsive firing device, a tapering hole will be produced below the lower end of the borehole. Thereupon the apparatus illustrated in FIGS. 1A and 1B is pumped down the borehole until it protrudes into the tapered hole left by the detonated shaped charge. Drilling fluid is circulated prior to the time that the apparatus illustrated in FIGS. 1A and 1B is so inserted in order to remove detritus produced by the shaped charge. Hydrostatic pressure is then again increased until shear pin 31 is sheared to detonate explosive charge 13. The upwardly-going energy produced by detonation of the explosive charge 13 will not have reached explosive charge 12 by the time that blasting caps 56 detonate the explosive charge 12. The energy produced by the explosive charge 12 will for the most part be directed downwardly and outwardly so as to deflect the upwardly-going energy produced by explosive charge 13. Thus, the energy produced by both of the explosive charges will be more effectively utilized.

Preferably, the shape of the cupped explosive charge 12 is that of a paraboloid of revolution, as it has been found that this shape is most effective in achieving the desired results.

Manifestly, while the electrical firing device shown is preferred, other types may be utilized, such as delay blasting caps of the type illustrated in The Science of High Explosives, M. A. Cook, Reinhold Publishing Co., New York, pp. 16-17. In this case the blasting caps may be activated simultaneously, and the time interval between detonation of the explosive charges will be determined by the inherent delay provided by the blasting caps.

The above description and examples of the invention are for the purpose of illustration, and it is not intended that the invention be limited except by the scope of the appended claims.

What is claimed is:

1. Apparatus for use in earth drilling, comprising:

an elongated housing;

nondirectional first explosive charge means at the lower end of said housing;

a thin cup-shaped supporting member positioned in said housing above said explosive charge means, extending outwardly from the axis of said housing and upwardly and away from said explosive charge means;

a second explosive charge means lining the inner surface of said supporting member;

first detonating means connected to said first explosive charge means;

second detonating means connected to said second explosive charge means adapted upon activation thereof to detonate said second explosive charge means a predetermined interval after activation of said first detonating means and before the energy produced by detonation of said first explosive charge means reaches said second explosive charge means; and

means for simultaneously activating said first and second detonating means.

2. Apparatus for use in earth drilling, comprising:

an elongated housing;

nondirectional first explosive charge means at the lower end of said housing;

a thin cup-shaped second explosive charge means positioned in said housing above said first explosive charge means and extending outwardly from the axis of said housing and upwardly and away from said first explosive charge means;

first detonating means connected to said first explosive charge means;

second detonating means connected to said second explosive charge means adapted upon activation thereof to detonate said second explosive charge means a predetermined interval after activation of said first detonating means and before the energy produced by detonation of said first explosive charge means reaches said second explosive charge means; and

means for simultaneously activating said first and second detonating means.

3. Apparatus for use in earth drilling, comprising:

an elongated housing;

nondirectional first explosive charge means at the lower end of said housing;

a thin cup-shaped second explosive charge means positioned in said housing above said first explosive charge means and extending outwardly from the axis of said housing and upwardly and away from said first explosive charge means;

first detonating means connected to said first explosive charge means;

second detonating means connected to said second explosive charge means adapted upon activation thereof to detonate said second explosive charge means a predetermined interval after activation of said first detonating means and before the energy produced by detonation of said first explosive charge means reaches said second explosive charge means;

means for simultaneously activating said first and second detonating means;

said cup-shaped explosive charge means being in the form of a paraboloid of revolution.

4. Apparatus for use in earth drilling, comprising:

an elongated housing;

nondirectional first explosive charge means at the lower end of said housing;

a thin cup-shaped second explosive charge means positioned in said housing above said first explosive charge means and extending outwardly from the axis of said housing and upwardly and away :from said first explosive charge means;

first detonating means connected to said first explosive charge means;

second detonating means connected to said second explosive charge means adapted upon activation thereof to detonate said second explosive charge means a predetermined interval after activation of said first detonating means and before the energy produced by detonation of said first explosive charge 5 6 means reaches said second explosive charge means; 704,465 7/1902 Kirsanov 10224 means for simultaneously activating said first and 2,363,234 11/ 1944 D011 10220 X second detonating means; and 2,543,823 3/ 1951 Barry 166-5 5 .5 means within said second explosive charge means for 2,609,750 9/1952 McFarland 10223 reflecting outwardly the energy released upon detona- 5 2,671,400 3/ 1954 Duesing 10224 tion of said second explosive charge means. 2,775,940 1/ 1957 Klotz 10223 3,022,729 2/ 1962 Robinson 10220 References Cited by the Examiner UNITED STATES PATENTS BENJAMIN A. BORCHELT, Primary Examiner. 60,573 152/4866 Sh ff r 10223 10 AM RG, Ex min r- 87,372 3/1869 Shalfner 10223 V. R. PENDEGRASS, Assistant Examiner. 

1. APPARATUS FOR USE IN THE EARTH DRILLING, COMPRISING: AN ELONGATED HOUSING; NONDIRECTIONAL FIRST EXPLOSIVE CHARGE MEANS AT THE LOWER END OF SAID HOUSING; A THIN CUP-SHAPED SUPPORTING MEMBER POSITIONED IN SAID HOUSING ABOVE SAID EXPLOSIVE CHARGE MEANS, EXTENDING OUTWARDLY FROM THE AXIS OF SAID HOUSING AND UPWARDLY AND AWAY FROM SAID EXPLOSIVE CHARGE MEANS; A SECOND EXPLOSIVE CHARGE MEANS LINING THE LINNER SURFACE OF SAID SUPPORTING MEMBER; FIRST DETONATING MEANS CONNECTED TO SAID FIRST EXPLOSIVE CHARGE MEANS; SECOND DETONATING MEANS CONNECTED TO SAID EXPLOSIVE CHARGE MEANS ADAPTED UPON ACTIVATION THEREOF TO DETONATE SAID SECOND EXPLOSIVE CHARGE MEANS A PREDETERMINED INTERVAL AFTER ACTIVATION OF SAID FIRST DETONATING MEANS AND BEFORE THE ENERGY PRODUCED BY DETONATION OF SAID FIRST EXPLOSIVE CHARGE MEANS REACHES SAID SECOND EXPLOSIVE CHANRGE MEANS; AND MEANS FOR SIMULTANROUSLY ACTIVATING SAID FIRST AND SECOND DETONATING MEANS. 